1. Field of the Invention
The present invention relates to a method and system for adaptively controlling a laser-based material processing process and method and system for qualifying same.
The present description generally relates to laser-based repair of semiconductive substrates and process control thereof.
2. Background Art
Laser-based repair machines improve yield of various semiconductor processes. Repair machines may also be interfaced with electrical or visual test equipment. Test equipment outputs are used to control the repair process.
For example, an early laser-based IC mask repair method and system is disclosed in U.S. Pat. No. 4,727,234 (the '234 patent).
Published U.S. Patent Publication No. 2005/0282299 (the '2299 publication) entitled “Wafer Inspection System And Method Thereof” exemplifies increased “in-line” automation of a semiconductor fabrication process during a “pre-laser” process. Various defects are automatically detected and sorted using various algorithms. FIG. 1 herein (corresponding to FIG. 1 of the '2299 publication) is a block diagram of a wafer inspection system according to an embodiment of the '2299 publication. As shown, the system may comprise an electrical testing subsystem 10, a defect detecting subsystem 20, a defect sorting subsystem 30, and a defective determining subsystem 40. The electrical testing subsystem 10 can control a probe to be in contact with a pad of a die after loading a die-mounted wafer thereon, and can perform a predetermined electrical test process. Here, the electrical test process may include a burn-in process to test the durability of the die, a pre-laser process to supply an electrical current to the die to check a defective die according to an operation state, and a laser repair process to scan and repair the defective die with a laser, etc.
Memory repair is an example of a valuable manufacturing process used to improve the yield of memory chips. By way of example, general information on link blowing is available in LIA HANDBOOK OF LASER MATERIALS PROCESSING, Chapter 19, pp. 595-615, “Link/Cutting Making,” Ed. in Chief Ready, Laser Institute of America, 2001. As indicated on page 595, individual links, identified by Automatic Test Equipment (ATE), are cut with a focused laser.
Japanese patent publication JP1083390 discloses a laser beam machine for cutting fuses and including a detector for measuring light reflected from a cut fuse.
U.S. Pat. No. 5,555,495 discloses adaptive control of a system with a human in the loop.
Prior repair systems include manual inspection. The information for inspection is typically obtained from a microscope system or SEM. The inspection equipment may include a computer and display. However, intermittent checks limit yield.
Therefore, present memory repair and other laser-based repair machines (1) rely upon the ATE to provide all defect information and (2) do not include closed loop control of the repair process.